taikowaza

I have a chance to get a great deal on diffs
4.88 IFS front diff with truetrac, and 4.88 rear diff open carrier.
only problem is, the diffs are for a 4cylinder. my application is a v6

question: can I put the complete 4 cylinder front and rear diffs in my 6cyl 2nd gen? all gears already installed
another question: I am going to put a truetrac in the rear as well (I know, I should get air lockers, but for what I do, dual truetracs are great, apologies in advance!)

the question is, if the v4 rear 4.88 diff will fit, that means that I will also need a 4cylinder truetrac in the rear, right?

is there a strength issue with this (v4 vs. v6), should I wait on these diffs, or go for it?

thanks guys
T

jimmyray

first off it would be an in-line four cylinder, and i am pretty sure that the running gear is verey diff. but i might be wrong on that. If its for the 4 then it might not be as strong as the v6 equip.

Toyopnoy

If you are getting the whole third member then yes they are interchangeable. Just completely swap the thirds.

slosurfer

It shouldn't be a problem mix and match front to rear. Remember all the SAS toy axles are 4 cyl. Just remember which is the 4cyl. so that if you ever regear, you buy the correct gears.

Marc P

I have read they are not as strong...2 pinion vs 4 pinion on the V6

4Crawler

iTrader: (3)

If swapping in a TrueTrac, you essentially negate almost all differences in the 4 vs. 6-cyl diff. The TT replaces the entire carrier and then the only difference is the gear set.

spaceycayce

Well after a nice chat with the shop doing my SAS a lot of stuff is interchangable. I am currently running 5.29's with ARB's 4 cyl in the front. The rear is a little more fun and I'm putting in 5.29's with ARB's in a 4cyl housing w/ v6 diffs and drums. Since my v6 housing is FUBARed and my rig is Auto we had a few issues pop up. I have an 85 rear donor axle that went with the front one. We are swapping out the V6 diff and putting it in the 85 housing. It fits perfect we were working with it today. Now the other problem we had was the 85 drums and backing plates were FUBARed too. So after a few calls we found out that we could use the shorter 85 shafts and transfer over the ABS drums from the v6 axle, he was worried about it seating right but it fit well. I love how Toyota parts are interchangeable. So the bearings are currently being repacled on it now and the axle should be done early next week. I hope this helps some.
Good Luck with yours

Ganoid

Yup they will bolt right up as everyone said. The only problem you may have is if its out of an older truck. I'm fairly certain that your 92' in the sig has ABS and the older 4cyl thirds didn't come with a spot for the ABS sensor. If the 4cyl third is out of a newer truck like you have then there is likely to be a sensor hole in the 3rd.

AxleIke

Yes, you can interchnage thirds.

Toyota has not made a v4 engine sold in the US, AFAIK.

With truetracs, you are the same strength. The difference in the gear sets will be minimal. Strength becomes an issue when running lockers and big tires, or have a corvette engine or something swapped in.

This applies only to swapping in thirdmembers. If you tried to instal a 4cyl diff into a 6cyl third, you would run into some issues with the bearing sizes.

anthony1

iTrader: (1)

IMHO, I would not put 4 clyn diff in a v6. Most people do it the other way around as an upgrade for strength. As for the front, I think it's the same for both.
If you have IFS, the front is not interchangable with the rear. IFS diff is 7.5 while the rear is 8.0.
As Ganoid said, check for the speed sensor hole or you'll have to hang up the sensor. If you cut off the sensor, the Antilock light on the dash will constantly be on.

Regarding swaping the 85 housing into 2nd gen, the 85 housing is 3" narrower than the V6 housing. Most guys swap out the older housing for the wider one for stability.

taikowaza

Thanks for all the great advice.
I've got a report to give,
the way I found my parts is I set up an RSS feed so that anytime someone posted anything in auto parts on craigslist about "toyota 4.88" it would flag me.

so, I've been getting emailed everytime someone sells something in my area with 4.88 gear ratios.
I got an email a few weeks ago about someone selling a front IFS v4 4.88 diff with yukon gears and a truetrac installed! Pretty awesome, total price $400.

then, I needed a rear and posted on craigslist, and the next day was offered a rear 4.88 4cyl diff in great condition for $200 delivered to my house. I bought a rear truetrac off of 4wheel parts for $350 and got a $50 coupon(they are having a promotion).

I took the diff and truetrac to Randy's Ring and Pinion near Seattle yesterday and they set up the whole thing with new Timken bearings for $200. When I throw the 3rds in, I'm selling my stock 4.56 diffs for $100 each.

so, all in all, total cost for front and rear 4.88 regear and dual truetracs installed= $1000.
I'm happy because this is a lot less than I was quoted for a full job at the local offroad shop. I would highly recommend watching craigslist for used or sale items to come up. RSS feeds are a great way to keep an eye on things!

thanks again for all the advice and I will post pics once I get everything installed.
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The only slightly disappointing thing is that while the front gears are Yukon, the rear gears are Genuine. Although I was wary about these, the guys at Randy's assured me that they were in awesome shape and that unless I am running really big tires, that I would not know any difference, that as long as gears are set up well that they should have a long life and be silent. I briefly considered pulling the genuine gears and installing yukons instead, but they assured me that with the timken bearings and the pro setup that they would be fine...I hope they are right, they said the machining lines were still very visible (indicating a relatively new ring and pinion apparently) and that they expected no problems. I hope that I made the right choice

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on another note, everybody at Randy's spoke very highly about truetracs, said that they are extremely strong, transparent on the road, and for non rock crawlers like me they are great. I like that they completely replaced the open carrier and that they negate any strength difference between the v4 and v6 diffs.

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one last thought-
In the manual it says: "Use extreme caution when accelerating or decelerating on slippery or unstable surfaces. Vehicles/axles equipped with traction differentials are inherently more sensitive to side-slip than vehicles equipped with conventional differentials. Stability can be regained if side-slip occurs by letting off the accelerator".
I need to educate myself about this some more in order to adapt my driving accordingly.

Apologies for the long post, I'm enjoying this whole process it has been a blast so far.

T

taikowaza

Thanks to your help we were indeed able to swap out the 4.56 OEM V6 3rd members and pop in the V4/4.88 Truetrac 3rd members. It took most of the day and I took advantage of draining the transfer case and filling it with a combo of Royal Purple and MT-90 (ran out of MT-90 and the redline dealer was out of town) seems to work great so far. Thanks to my buddy who has a lot of skill and awesome tools. AIR tools made a HUGE difference!!

used Royal Purple 75W90 for the diffs, they went in no problem as you all assured me they would. The only problem (if it is really even a problem) was that the ABS is no longer active in the rear as there was no place for it in the 4cyl diff as Ganoid predicted! The light is not on though which is a bonus. In the front diff the original ADD attachments are now off, leaving no trace of their stock presence. I am much happier with the manual locking hubs anyway and it's nice to remove all remnants of the ADD...excess baggage!

First impressions- a lot more power! the 4.88s on 32x11.5s are really nice! I have more low end torque and my powerband has moved into a much more usable range. I was jamming it on the highway and really having fun, I will have to watch my foot. The RPMs are great and I'm really happy with this mod.

The rear truetrac is totally transparent, I feel (maybe psychological?) that it is tracking straighter and feels more gripped...but it's prob. in my mind!
The front TT on the other hand is going to take some getting used to IMHO. of course when the hubs are disengaged there is no difference from open diff, but when I engaged the hubs and went 4HI I could REALLY feel them, it was much harder to turn the steering wheel and I had resistance for sure. I had to spend much longer on the turns. Maybe this is because I was on pavement? will it be different on gravel/snow etc, perhaps I should not even engage the TT/hubs on dry roads? I don't think I would feel comfortable driving on a highway with front hubs/4wd active as my reaction times seem ver. different.

Ganoid

You really want to stay out of 4wd on high traction surfaces like pavement (unless its covered with snow). Take the truck out into a wet field or on a gravel road and try it again. Even a 4wd with open diffs will bind up tight and possibly break a T-case chain going around a corner on high traction surfaces so I can only imagine how yours felt. If you want to feel the front TruTrac work get out into a muddy field or gravel road like I mentioned and hammer the throttle to try and get some wheel spin (at least in the rear). You will feel the front end try and pull its self straight as the steering wheel has an almost self centering force. Deep snow and sand is where you will feel the front TruTrac the most.


Edit...You may also want to change gear oil in the rear diff in a few hundred miles if the gears still have machine marks and are not yet broke in. Usually you try and avoid prolonged high speed travel with new gears for the first few hundred miles. Stop and go traffic and 4 wheeling if you can believe it are actually just fine for new gears as there is little heat build up.